Project Summary The perception of emotion starts with emotion detection, which reflects an ability to determine whether emotional content is present. The detection of emotional information is evolutionarily relevant, in that it allows for a rapid behavioral response when faced with threat. Emotion detection (and its relation to immediate threat) has primarily been studied with adults and very little is known about the development of this critical ability. The K99 portion of this proposal seeks to remedy the situation by testing infants for detection of emotional content in very brief stimulus presentations (50ms, 100ms, 200ms, 400ms). The infants will be tested using happy, angry, and fearful facial expressions and saccade latencies to different emotions will establish whether they are differentially detected; specifically, if threat-related emotions (i.e., anger, fear) are detected faster than non- threatening emotion (happiness). Additionally, eye-tracking and pupillometry measures will determine whether infants are utilizing specific features to detect distinct emotions and whether pupil diameter, an index of autonomic nervous system (ANS) function, is altered by emotional faces. Most importantly, the R00 phase of this award will be used to study a longitudinal sample to assess individual differences in detection speed across development and determine whether these relate to later developmental abilities. Candidate: The candidate has her Ph.D. in Experimental Psychology and has 2 years of postdoctoral research experience. She has a strong publication record despite a 4-year absence from her field due to health issues. With this award, she will reach her potential to become a successful independent investigator. Training: Specific training in the acquisition and analyses of eye-tracking data and the related measures of pupillometry will be useful in her pursuit of a tenure-track position at a Research I/Doctorate Extensive university. Becoming comfortable using MATLAB and conducting analyses using advanced statistical methods will be appropriate training aims to facilitate this goal. KU?s Life Span Institute is an interdisciplinary research center focused on development across the life span, and its collaborative environment will provide an ideal setting for the proposed research. Research: Using a cross-sectional study with 3.5- and 7.5-month-old infants, the proposed research will document the time course of emotion detection, potential preferential processing of threat-related emotions, how low-level visual features influence detection, and how ANS activity is differentially modulated by emotional content. The R00 phase will add an additional visit at 12.5 months and a follow-up assessment at 18 months. This study will establish cross-age stability across measures and examine their predictive validity for developmental outcomes. Documenting the development of this vital skill in early infancy has potential implications in the study of typical and atypical development, such as that in autism spectrum disorder.